Rotary percussive drill control



United States Patent Inventor John L. Nagely Sidney, Ohio June 20, 1968 Dec. 15, 1970 Westinghouse Air Brake Company Wilmerding, Pa.

a corporation of Pennsylvania ROTARY PERCUSSIVE DRILL CONTROL 9 Claims, 5 Drawing Figs.

U.S. Cl

Int. Cl. Field of Search AppL No. Filed Patented Assignee [56] References Cited UNITED STATES PATENTS 1,658,330 2/1928 Gilman 173/105X 1,662,792 3/1928 Osgood 173/105X 1,689,596 10/1928 Osgood 173/105X 2,355,357 8/1944 Adams 60/51X 2,731,796 l/1956 Sublett.... 60/51 3,058,310 10/1962 Panissidi 60/51X Primary Examiner-Nile C. Byers, Jr. Attorney-Lieber and N illes IIIIIIIIII PATENTED 0501 51970 SHEET 3 OF 3 ROTARY PERCUSSIVE DRILL CONTROL RELATED PATENTS The present application is related to U.S. Pat. No. 3,230,7l1, 3,230,711, dated Jan. 25, 196.6 to James C. Swain, George E. Manning,and David L. Thomas.

BACKGROUND In the drilling of rock and ore, it is customary to employ percussive drilling tools which utilize pressurized fluid for delivering a succession of impact blows to a striking element which, in turn, transmits the same to a drill steel chuck for performance of the work. In most instances, these devices have heretofore utilized pneumatic motors operable by compressed air as the power source. However, it has more recently been proposed to use percussive drills poweredby hydraulic fluid under pressure and acting on a reciprocating piston to motivate the striker, and one such hydraulically actuated drill is shown and described in the above-identified patent.

As also disclosed in U. S. Pat. No. 3,230,7ll,it has additionally been proposed to provide means for selectively imparting rotation to the drill steel chuck along with the percussive operation thereof. In such rotary-impact or rotary-percussive drills, it is desirable to provide for independent regulation of both the rotary mode and the impact mode of operation due to differences in conditions and operational requirements. This requires that the drill steel chuck be supported for both reciprocating and/or rotational movement and that means be provided for selectively effecting such movements simultaneously and/or independently.

it is furthermore necessary in these fluid-actuated drilling devices to provide means for advancing the drill steel, and thus the drill bit, toward and into operative working position, as well as to provide means for feeding the drill as the work is being performed and for withdrawing the same from the work when desired. Again, since working conditions are variable, dependent upon numerous factors, the feed means for the drill must be independently controllable to adapt the same to such varying conditions.

in addition, it is desirable in such devices to provide means for roof bolt tightening, and it is especially advantageous and convenient to incorporate the actuating means for the roof bolt tightening mechanism directly in and as an integral part of the drill assemblage and to utilize a common power means therefor.

While the above-identified and related patent embodied means for accomplishing the aforesaid advantageous and desirable functions and features, the present invention provides various improvements thereon, and particularly in the controls therefor.

SUMMARY Accordingly, the present invention contemplates the provision of an improved hydraulic system for a rock drill by means of which all of the above-indicated desirable functions may be accomplished and controlled in a highly efficient manner.

Another object of this invention is to provide an improved hydraulic control system for a rotary-percussive stoper or similar-type drill wherein separate and independent sources of hydraulic fluid pressure are utilized for imparting rotation to the drilling element, for imparting percussive action to the drilling element, and for feeding the drilling element during the performance of its work.

Still another object of the invention is to provide an improved hydraulic control system wherein flow of pressurized fluid from all three of the aforesaid separate and independent sources is selectively controlled in a novel and efficient manner by improved valve means operable through a single actuator to and from a neutral position, collaring position, and drilling position respectively.

A further object of the present invention is to provide an improved control system for a hydraulically operable rock drill wherein rotary and/or percussive action as well as drill feed may be selectively controlled, adjusted and automatically regulated for rotary and/or percussive drilling operations as well as roof bolt tightening, and wherein means is also provided for independently and rapidly positioning the drilling element.

These and other objects and advantages of the invention will become apparent from the following detailed description.

THE DRAWINGS A clear conception of the several features constituting the present invention and of the mode of operation of a typical hydraulically actuated stoper drill embodying the improvements may be had by referring to the drawings accompanying and forming a part of this specification, wherein like reference characters designate the same or similar parts in the various views.

H6. 1 is a side elevational view of a typical stoper-type rock drill to which the improved hydraulic control system of the present invention is applicable;

FIG. 2 is a vertical transverse section through the drill of FIG. 1 taken generally along the line 2-2 thereof;

FIG. 3 is a vertical transverse section through the drill motor taken generally along the line 4-4 of FIG. 1;

FIG. 4 is a transverse section through a typical roof bolt tightening device adapted for operation by the drill through use of the control system;

FIG. 5 is a schematic diagram of the hydraulic drill control system constituting the present invention.

DETAILED DESCRIPTION Referring to the drawings, a typical rotary-percussive drill of the type adapted to be operated and controlled by the improved hydraulic system constituting the present invention is shown in FIGS. 1 and 2. Since the hydraulically operable rotary-percussive stoper-type drill thus shown for purposes of illustration is fully disclosed in U.S. Pat. No. 3,230,711, dated Jan. 25, 1966 to James C. Swain, et al., reference is herein made to such prior patent for a detailed description of the structure and mode of operation thereof. Likewise, since the roof bolt tightening device of H0. 3 is more fully disclosed in this prior patent, reference may be made thereto for additional structural details of suchdevice.

Generally speaking, the rotary-percussive drill shown in FIGS. l and 2 comprises a drill motor 20 mounted on a support and feed structure 22 and having a drilling element 24 projecting therefrom for rotary and/or percussive operation.

The drill motor 20 is supported for axial movement by the feed structure 22 which comprises generally a pair of laterally spaced feed cylinders 26 bracketed together in parallelism by a pair of vertically spaced crosspieces 28,30 to provide a support, the drill motor being secured to the support thus provided in a suitable manner to form a rigid assembly.

Extending through the lower end of each of the cylinders 26 is a double-acting power piston 32 adapted for simultaneous actuation by fluid under pressure conducted to the displacement chambers 34 selectively above or below the confined heads 36 of the pistons by way of upper and lower fluid pressure supply conduits 38,40 respectively.

Simultaneous extension and retraction of the cylinder piston units 26,32 is accomplished under the control of an operator, and the lower outer ends of the pistons 32 are coupled to an articulatable foot 42 as disclosed in detail in U.S. Pat. No. 3,246,706, dated Apr. 19, 1966, to Albert Feucht et al.

The drill motor 20 which is rigidly secured to the cylinders 26 is, in turn, connected to the lower foot-carrying bracket 44 as by a pair of chains 46 and tie rods 48, each chain traversing one or more sheaves 50 rotatably supported at the upper end of the bracketed cylinders 26 of the feed leg assembly 22, and by virtue of the feed structure thus described, the cylinders 26 of the telescopic feed are adapted to move simultaneously relative to the pistons 32 as fluid under pressure is admitted to the displacement chambers 34. in addition, a pair of cables 52 are preferably secured between the motor 20 or cylinders 26 and the upper ends of the tie rods 4% with the intermediate I portions of the cables traversing a pair of sheaves 54 to aid in stabilizing the device and prevent chain kinking or possible binding of parts during movement.

By reason of the support and feed structure thus described and as disclosed in detail in US. Pat. No. 3,246,706 hereinabove identified, the drill motor 20 is supported for f'r'hovement toward and away from the work.

For a detailed description of the construction and operation of the drill motor 20, reference may be had to US. Pat. No. 3,230,711 hereinabove identified. However, as shown in MG. 3,,this motor comprises generally a housing 58 carrying a drill steel chuck 60 in the front or upper portion thereof, the chuck 60 being supported within the housing for both axial and rotative motion. The chuck 60, in turn, carries a drill steel 62 having a work performing bit 64 at its free end. A striker piston 66 is mounted within the housing 58 for reciprocatory movement toward and away from the drill steel chuck 60, and suitable means is also provided for reciprocating the striker 66 to impart a succession of blows to the chuck 60 and thereby percussively actuate the same.

As shown and described in detail in 68 aforesaid U.S. Pat. No. 3,230,711, the means for driving the striker 66 toward and into contact with the chuck may comprise a hydraulically actuated impact piston 68 slidably carried by the housing, the impact piston 63 being disposed concentrically with the striker 66. This impact piston 68 is actuated by pressurized hydraulic fluid conducted thereto from a suitable supply .source via inlet 70 past an accumulator 72 under the control :ofa reciprocating spool-type valve 74. Thus, in operation, the impact piston 68 is reciprocated by fluid pressure admitted to conduit 70 past valve 74, and on its forward motion, this im- :pact piston 68 drives the striker 66 toward and against the "chuck 60,,the striker being returned to starting position after each forward stroke as by means of a spring 76 to thereby impart a succession of percussive blows to the chuck, and as long as the drill bit 64 is firmly held against the work, the blows delivered by the striker are transmitted by the chuck to the drill steel 62 and drill bit 64.

1 In addition to the percussive action which may be imparted to the drill chuck 60 and drilling element 24 which comprises the drill steel 62 and bit 64, the chuck is also mounted for "selective rotary motion by a rotary hydraulic gear unit adapted to be driven by fluid pressure entering an inlet conduit 32. Fluid pressure conducted through conduit 82 is adapted to drive gears 34 of the unit d0 which, in turn, drives a member $6 meshing with gear 8%, the member lid having a sliding spline connection 0 with the chuck 60 to, in turn, rotate the same.

Thus, the chuck 60 is percussively actuated through the striker 66 actuated by the impact piston 6% by fluid pressure admitted through conduit 70, and the chuck 60 may also be the work and is fed thereto by the feed leg assembly 22.

I In addition to its drilling operation, the drill is also adapted tddrive a bolt tightening device such as shown, for example, in

4, and for a detailed description of such mechanism,

freference is once again made to U.S. Pat. No. 3,230,711. This bolt tightening device comprises, in general, a housing 9d "adapted for attachment to the upper end of the motor by "rnleans of a coupling member 96 receivable by the chuck 60 in place of the drill steel 62, the coupling member being thereby adapted for rotation in the same manner as hereinabove -described with respect to rotation of the drill steel. Rotation of "the coupling member 96 is imparted through shaft )0 to a gear I00 which meshes with a gear 302 to drive the same. The gear 102, in turn, carries a gear llld which meshes with and drives a gear ring 106 which rotates a support 10% splined to the gear ring i106. The support 10% is provided with an outwardly exposed upper recess 110 adapted to removably receive a bolt head engaging unit 112 which has an outwardly open recess lid of predetermined shape and size for engaging a bolt head, not shown, to be tightened by rotation.

Thus, when it is desired to utilize the drill for roof bolt tightening, the housing 94 may be attached to the chuck 60 in place of the drill steel 92, and upon rotation of the chuck 60 by fluid pressure, the roof bolt tightener will be operated to impart rotation to a roof bolt, the head of which is received within the recess 1 1d of the member 112.

Now, referring to the hydraulic control system for the stoper-type drill, such system is illustrated'schematically in FIG. 5, and includes three separate sources of hydraulic fluid pressure for actuating the drill through its several operational modes. For rotary operation of the drill steel chuck 60, power is derived from a suitable variable displacement, pressure compensated and servocontrolled pump L20 of relatively large volume capable of operation to 3,000 p.s.i. For percussive operation of the chuck. 60 and its attachments, a fixed displacement pumping unit 122 of any suitable type which may be of smaller volume and capable of operation at 2,000 p.s.i. may be utilized as the power source. For drill feed, the source of power may comprise another small volume fixed displacement pumping unit 124 having a capability on the order of 2,000 p.s.i. Hydraulic fluid may be supplied to the pumps 120,l22,l24 from a suitable supply reservoir.

The pump E20 supplies hydraulic fluid under pressure to the conduit 1126 while pump 122 supplies pressurized hydraulic fluid to the conduit 128 and the pump 124 supplies pressurized hydraulic fluid to the conduit 130; The conduits 126, 128, 130 all communicate with a main valve 132 which is preferably of a single-spool-type actuated by means of a single operating lever 134 which may be mounted on a control box located in the vicinity of the drill. The spool valve 132 is adapted to be manually moved through its connection with the lever R34 to and from a neutral position wherein all of the pumps R20, 122, 124 are unloaded, collaring position which provides for slow rotation of the drill chuck independently of the flow control setting as well as high drill bit percussion and slow drill feed, drilling position which provides for a preset rotary speed for the best drilling rate dependent upon conditions as well as a preset feed pressure and flow and full bit percussion, and bolt tightening position and operation with the roof bolt tightening mechanism. For convenience, it has been found that in neutral the lever 134 be in vertical position, that the next forward position of the lever 134 places the valve in position for collaring, that the next forward position of the lever l34l places the valve in drilling position, and that for bolt tightening, the lever be designed for shifting in a reverse direction from its neutral position.

With the drill valve 132 in neutral position as shown in FIG. 5, essentially an open center system is provided in which the conduits l26,l2d,130 are all blocked by the valve 132. A spring-loaded combination relief and unloading valve 138 communicates with feed leg pressure conduit 130, and with the unloader line blocked, zero pressure is exerted and the spring bias opens the valve 138 so that the pump discharges to tank. When pressure is added to the unloader line, the unfor rotary operation is also blocked by the drill control valve 132, and when in neutral position, an independently operable drill positioning valve 142 located downstream of the valve 132 also blocks flow from conduit 3% and branch 150.

thereof. A spring-loaded discriminating valve 144 is also interposed in conduit 126 downstream of the positioning valve:

142, and in neutral position of the drill valve, the discriminating valve 144 opens the conduit 126 to the down side of the feed leg cylinders 26. Since the drill is only positioned when the drill control is in neutral position, this is the situation which exists for drill positioning. Also'interposed in the conduit 126 is a safety valve 146 which assures against overloading of this circuit.

With the drill valve 132 maintained in neutral position as described, the drill positioning valve 142 may be manually operated through a lever 148 to shift the same for either up or down operation of the feed legs 26. To lower the drill, the positioning valve 142 is shifted to the right as viewed in FIG. 5 to block branch conduit 150 and connect-conduit 126 to the small area side of the feed cylinder 26 below the piston head 36 via conduit 40 while the upper large-area side of the cylinder 26 is connected through conduit 38 to the exhaust pressure. Since the pump 120 has a large capacity and a pressure level of about 2,000 p.s.i., this action is immediate. To raise the drill, the positioning valve 142 is shifted to the left and thereby opens the upper large area side of the feed cylinder 26 above the piston head 36 to conduit 126 via its branch 150. In this connection, it should be noted that the servovalve 156 and servopiston 170, which are hereinafter more fully described, are inoperative and that the variable volume pump 120 operates at zero displacement and 2,000 p.s.i. The drill positioning lever 148 for operating valve 142 independently of the main drill valve 132 is used to back thedrill out of a hole after drilling'is completed as well as for bringing the drill steel and bit 64 into engagement with the rock prior to initiating the drilling action. This positioning lever and valve is also used for rapidly bringing the removable bolt tightener 94 into engagement to tighten the roof bolt and for removing the same.

When it is desired to bring the drill into collaring position in order to make it easier for an operator to start a hole, the valve 132 is shifted to the right by means of lever 134. The valve 132 thereupon connects conduit 126, metered through valve 132, to line 152 and flow control 154, with conduit 82 communicating with the rotary gear motor 80 for rotating the drill steel chuck 60. At the same time, conduit 128 is connected to conduit 70 for operating the percussion .motor 20, and the conduit 130 is connected via line 153 and valve 142 with conduit 38 communicating with the upper part of cylinder 26 above the piston head 36 to. operate the feed leg. The collaring position thus described is predicated on slow rotation, high percussion and a modest feed rate, dependenn'however, upon drilling conditions. Thus, the unloading valves 138,140 for feed relief and percussion relief respectively are backed off by pressure existing in the conduit 152, and these valves will then operate normally as system relief valves with valve 138 being conveniently adjustable to the desired limit of feed leg pressure. The pressure in the circuit through bypass 160 which communicates conduit 152 with the hydraulic actuator 162 for valve 144 thereby shifts the discriminating valve 144 to the left to block flow of fluid from conduit 126 and connects conduit 130 to conduit 40 and thus opens the lower small area side of the feed cylinder below the piston head 316 to conduit 130. Flow through the circuit comprising conduits 126,152 to the rotary motor is metered through valve 132 for slow rotation independent of the flow control valve setting and the differential within the lines 164,166 from conduit 152 to springloaded servovalve piston 168 and hydraulic servovalve piston 158 respectively is insufficient to make the servovalve 156 operable and cause servopiston 170 to become inoperative. Thus, the variable volume pump 120 remains on the setting of the compensator 170 to provide the required flow as determined by metering of drill valve 132 to rotary motor 80. As indicated, the percumion circuit through conduit 128 and 70 is fully open to percussion motor to provide for full percussive function. Thus, in such collaring position, the drill chuck and the parts carried thereby are slowly rotated by pressure fluid metered to the rotary motor while the chuck and its attendant parts are percussively operated at high speed with the feed leg being moved at a modest feed rate by pressurized fluid supplied through conduits 130, 154 and 38.

With the lever 134 moved to shift the valve 132 to drilling position, the flow through the valve 132 is the same as that hereinabove described with respect to collaring position. However, for drilling, the valve 132 is not metered to obtain lesser flow for the rotary motor function, and the flow control valve 154 setting having been previously adjusted for the drilling conditions is such as to cause differential pressures within lines 164 and 166 sufficient to unbalance the servovalve 156 and cause servopiston 170 to adjust the displacement of variable-volume pump and thereby provide the flow requirement for proper operation of the rotary motor. Thus, at the drilling setting, pressurized fluid issupplied from the pump 120 to conduits 126,152 and valve 154 to conduit 82 to provide the preset rotary speed affording the best drilling rate for existing conditions, while pressurized fluid is supplied from the pump 124 via conduits 130,153 and past valve 142 to the upper end of the feed leg 26 via conduit 38 to provide preset feed pressure to the feed leg, and full flow of pressurized fluid from the pump 122 is provided for full percussion by way of conduits 128,70.

If it is desired or found necessary to provide for rotary operation only of the drill bit, the same setting as hereinabove described for drilling operation is effected by means of the valve 132. However, the percussive action may be eliminated by providing a valve 172 in the percussion circuit which, when closed, causes unloading of the pump 122 by preventing the pressure in the circuit from conduit 152 from backing off the unloading valve 140. Thus, with the pump 122 unloaded, the percussion circuit is ineffective and the drill is adapted to perform a rotary drilling function without percussion.

For performing a bolt tightening operation, a device of the type shown in FIG. 4 is first applied to the chuck 60 in place of the drill steel 62, and valve 142 is thenshifted to the left by means of lever 148 to thereby raise and position the drill for the bolt tightening operation. The drill valve 132 is then also shifted to the left by means of lever 134, and fluid pressure from conduit 126'is thus metered through restricted opening in valve 132 to a conduit 174 and passes through a check valve 176 downstream of the flow control valve 154 and thus to the hydraulic rotary drill motor via conduit 82. In this position of the drill valve, all other ports are blocked. The flow control differential is zero and the servopiston 158 is inoperative with thevariable-volume pump 120 being on the compensator 121 at approximately 2,000 p.s.i. and providing only the displacement required for low rotary motor speed as determined by fixed restriction in valve 132. The maximum stall torque pressure is accordingly 2,000 p.s.i. A torque control relief valve 175 is included in the conduit 174 to limit the pressure applied to the rotary motor to a value commensurate with the bolt torque requirement. In this connection, 800 p.s.i. provides approximately foot pounds of torque on the bolt. It should be noted that the percussion and feed relief valves 140,138 respectively are not unloaded under this condition, but the time element for tightening a bolt is normally short and the fact that the relief valves are not unloaded is therefore not serious. Operation of the feed leg under these conditions is manually accomplished by the positioning lever 142 since no feed is required after the device 94 and socket 114 are positioned on the bolt to be tightened.

As distinguished from prior control systems for the type of hydraulically operable rotary-percussive drills shown herein, the present system employs separate and independent sources for hydraulic pressure fluid in the form of the pumps 120,122,124 for the rotary mode, impact mode and feed leg operation.

Accordingly, with the present system, rotation can be controlled by means of the flow control valve 154 from zero to any desired speed. The drill may thus also .be set for rotational operation according to particular circumstances such as the rock conditions on which the drill is operating, and the proper function is then performed automatically. It will be furthermore noted that when the main valve 132 is in drilling position, the small pump 124 is used for feeding the drill to the rock through the feed 26.-But, when the main valve is in the large variable-volume pump 120 is used to retain the feed leg of the drill in collapsed or distended position. The employment of the valve 172 for unloading the percussive fluid to tankto render the pump 122 inoperativealso permits the drill to be used initsrotary mode of operation without percussive action. Also, the present system permits the bolt tightener to be incorporated in the same hydraulic circuit as the drill operational circuit.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. A hydraulic control system for a rotary percussive stoper drill having fluid pressure feed means, said system comprising, a first source of hydraulic fluid pressure for imparting rotation to the drilling element, a second source of hydraulic fluid pressure for imparting percussive action to the drilling element, a third source of hydraulic fluid pressure for powering the feed means for the drilling element, valve means in fluid communication with said sources and for selectively controlling flow of pressurized fluid from all three of said sources of hydraulic fluid pressure to the drill, and means connected to said valve means for operating said valve means to selectively move the same to and from neutral position wherein all three fluid pressure sources are ineffective, or to a collaring position wherein all three fluid pressure sources are effective to slowly rotate and slowly feed the drilling element while normal percussive action is imparted thereto, and furthermoreto a drilling position wherein all three fluid pressure sources are effective to normally rotate the drilling element at a predetermined displacement pump, and the second and third sources of hydraulic fluid pressure each include a fixeddisplacement pump.

3. A hydraulic control system according to claim 2, wherein the first source of hydraulic fluid power includes servocontrolled pressure-compensating means for the output of the variable-displacement pump. 4. A hydraulic control system according to claim 1, wherein other valve means are in fluid communication with said third source of fluid pressure for independently feeding the drilling element toward and away from the work, said other valve means having a separate operator for moving the same.

5. A hydraulic control system according to claim 1, wherein the valve means is a unitary spool valve and the operator is a lever swingable to selectively move said spool valve to its several positions.

6. A hydraulic control system according to claim 1, wherein control means are in fluid communication with said first pressure source for selectively adjusting the setting of the first pressure source to provide for rotation of the drilling element at predetermined speeds when the valve means is moved to drilling position.

7. A hydraulic control system according to claim 6, wherein means is also in fluid communication with said third power source for selectively adjusting the setting of the third power source to provide for feeding the drilling element under predetermined pressures when the valve means is moved to drilling position.

8. A hydraulic control system according to claim 1, wherein another independently operable valve means is'in fluid communication with said second source for rendering the second source of hydraulic fluid pressure inefiective when the firstmentioned valve means is indrilling position.

9. A hydraulic control system according to claim l, wherein the drill includes a roof bolt tightener attached thereto and the valve means lS movable by the single operator to a fourth position wherein one of the sources of hydraulic fluid pressure is effective to actuate said roof bolt tightener. 

